1. Field of the Invention
This invention relates to an improvement of a reflector used in vehicle-mounted lamps such as a head lamp or a fog lamp and the like or an outdoor illumination or indoor illumination equipment and the like and a plane mirror or curved mirror of an optical equipment including a laser equipment.
2. Description of the Related Art
Although this kind of reflector (normally called as a reflector) in the prior art has used a relative safe Al alloy or Al having a floating film formed therein under application of oxygen adsorption effect of alkaline earth metal by mainly adding alkaline earth metals such as Mg, Ca, Sr, Li and the like, application of Al capable of attaining a high intensity of illumination at a low electrical power cost or Ag having a higher reflection factor than that of Al alloy with its reflection factor being reduced than that of Al has been studied in recent years.
However, it is widely known that since a stability or re-generating characteristic of the film of the floating member is aimed for the case of Al, or the floating member itself aims at an improvement of an oxidization of Al, this material is not necessarily stable against the non-metallic component such as halogen elements such as chlorine, for example, added to the surrounding atmosphere, resulting in that actually in the case that it is employed in the reflector, either Al or Al alloy film is covered by the resin protection film of acrylic system to form the reflector.
In view of the foregoing, although Ag has a high evaluation in the case that the reflector of high reflection factor is formed as material having a high reflection factor in a range of visible rays as compared with that of Al, it shows that it has a quite high reacting characteristic such as xanthation, chloride reaction with a large amount of sulfur, chlorine or oxidization added to the surrounding atmosphere and so it is called that it is hard to apply it as a reflector film. That is, when Ag is exposed in the surrounding atmosphere for a long period of time, it becomes silver sulfade (Ag2S) to cause its color to be changed black or it becomes silver chloride (AgCl) to cause its color to be changed white and to cause its optical characteristic to be deteriorated. Accordingly, if this material is exposed in the surrounding atmosphere for a long period of time, this shows a problem that an optical characteristic of Ag is deteriorated to cause its reflection factor to be reduced, so that it is said that this material is hardly applicable to illumination equipment or vehicle-mounted lamps and the like in recent years requiring a high intensity of illumination at a low electrical power cost.
In view of the foregoing, it has been proposed to provide, as a countermeasure to solve this problem and well-known in the art, a reflector having an improved wheatherability against sulfur and chlorine while keeping a high reflection factor by a method wherein an AgPd alloy reflective film having as its major component Ag added with Pd which is superior in its wheatherability with its amount being less than 30 wt % as well as a superior wheatherability such as chemical resistance which is hardly reacted with sulfur or chlorine, or an AgPt alloy reflective film having as its major component Ag added with Pt in its amount being less than 30 wt % is formed on a substrate acting as a supporting member (for example, refer to the Japanese Patent-Laid Open No. Hei 6-186407).
However, in such a prior art reflector as described above, although it is made apparent in reference to the result of an evaluation test that a high reflecting characteristic can be attained, it is not necessarily possible to say it sufficient that its wheatherability caused by discoloration or white muddy state under reaction with chlorine and sulfur and it still shows a problem not yet solved that its practical application is not sufficiently carried out.
That is, it is said that although Pd is a material showing a superior wheatherability which is hardly reacted with chlorine or sulfur as long as the material is not exposed in the atmosphere of high temperature and high humidity for a long period of time, this material may react with chlorine and sulfur if it is exposed in the atmosphere of high temperature and high humidity and there is a possibility that it may react with chlorine and sulfur to make chloride, xanthation and oxidization.
Accordingly, in the case that this material is applied in the vehicle-mounted lamps such as a head lamp or a fog lamp used in severe environment where its surrounding temperature is gradually increased as the time elapses, for example, and its humidity is also increased together with the temperature in a rainy day or the like, the material is exposed in the atmosphere of high temperature and high humidity for a long period of time, resulting in that there is a high possibility that its wheatherability is rapidly reduced and so it is a present situation that its more improved state is desired.
In addition, as described above, since the prior art reflector had a problem of uneasiness that it may be reacted with chlorine and sulfur to form chloride, xanthation and oxidization, resulting in that the reflector film was partially floated out of the substrate through this reaction to generate the film peeling-off phenomenon and had an inferior connecting characteristic (a close fitting force).
In addition, in the case that either Pd or Pt of 30 wt % was added in reference to the Japanese Patent Laid-Open No. Hei 6-186407, it was hard to say that the material was not at least appropriate material and could not be considered as an actual application as compared with the cost of Al or Al alloy due to the fact that market prices of both Pd and Pt were quite unstable and their costs were high.
This invention has been invented in reference to the aforesaid circumstances in the prior art, wherein it is an object of the present invention to provide a reflector in which a superior high reflection factor of Ag is restricted, a stable wheatherability can be attained in a continuous manner even if the reflector is exposed in an environment having severe high temperature and humidity, its connecting characteristic is effectively enforced, its practical effect is high and a high reliability can be attained.
In order to accomplish the subject matter, the present invention is constructed such that Pd acting as the second component is added to Ag acting as major component within a predetermined range, and an alloy reflective film having any one of these elements of Al, Au, Pt, Cu, Ta, Cr, Ti, Ni, Co, Si added as a third element within a predetermined range is formed on a substrate.
In addition, Pd acting as the aforesaid second element is added within a range of 0.5 to 3.0 wt % and any one of these third elements of Al, Au, Pt, Cu, Ta, Cr, Ti, Ni, Co, Si acting as a third element is added within a range of 0.1 to 3.0 wt %. In this case, a preferable amount of the second element is 0.7 to 2.3 wt % and more preferably 0.9 wt %. A preferable adding amount of the third element is 0.5 to 2.5 wt % and more preferably 1.0 wt %.
In the present invention, the aforesaid third element is Cu or Ti selected from any one of these Al, Au, Pt, Cu, Ta, Cr, Ti, Ni, Co, Si and an AgPdCu alloy reflector film or an AgPdTi alloy reflector film is formed on a substrate. In addition, a pre-treatment such as an organic ground film for improving a connecting characteristic with the reflector film is applied onto the substrate.
In the present invention, the aforesaid AgPdCu alloy or AgPdTi alloy is a sputtering target material or vapor depositing material and then either AgPdCu alloy reflector film or an AgPdTi alloy reflector film is formed on the substrate by the film forming process such as the sputtering process or the vapor deposition process.
Thus, in accordance with the technical means described above, it has been found that either AgPdCu alloy reflector film or an AgPdTi alloy reflector film, for example, in which Pd is added to Ag within a range of 0.1 to 3.0 wt % and further any one of these elements of Al, Au, Pt, Cu, Ta, Cr, Ti, Ni, Co, Si is added as a third element within a range of 0.1 to 3.0 wt % is formed on a substrate by the film forming process such as the sputtering process or the vapor deposition process, thereby occurrence of black spots or muddy white state through chloride formation, xathation and oxidization is prevented even in the atmosphere of high temperature and high humidity while keeping a high reflection factor and further the reflective film is prevented from being partially floated up from the substrate, resulting in that the alloy composed of three elements with this Ag being applied as the major component has its wheatherability substantially improved and a connecting characteristic with the substrate is effectively enforced.